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 * Copyright (c) 2013-2020, Esoteric Software LLC
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#ifdef SPINE_UE4
    #include "SpinePluginPrivatePCH.h"
#endif

#include <spine/IkConstraint.h>

#include <spine/Bone.h>
#include <spine/IkConstraintData.h>
#include <spine/Skeleton.h>

#include <spine/BoneData.h>

using namespace spine;

RTTI_IMPL(IkConstraint, Updatable)

void IkConstraint::apply(Bone &bone, float targetX, float targetY, bool compress, bool stretch, bool uniform, float alpha) {
    Bone *p = bone.getParent();
    float pa = p->_a, pb = p->_b, pc = p->_c, pd = p->_d;
    float rotationIK = -bone._ashearX - bone._arotation;
    float tx = 0, ty = 0;
    if (!bone._appliedValid) bone.updateAppliedTransform();

    switch (bone._data.getTransformMode()) {
        case TransformMode_OnlyTranslation:
            tx = targetX - bone._worldX;
            ty = targetY - bone._worldY;
            break;
        case TransformMode_NoRotationOrReflection: {
            rotationIK += MathUtil::atan2(pc, pa) * MathUtil::Rad_Deg;
            float ps = MathUtil::abs(pa * pd - pb * pc) / (pa * pa + pc * pc);
            pb = -pc * ps;
            pd = pa * ps;
        }
        default:
            float x = targetX - p->_worldX, y = targetY - p->_worldY;
            float d = pa * pd - pb * pc;
            tx = (x * pd - y * pb) / d - bone._ax;
            ty = (y * pa - x * pc) / d - bone._ay;
    }
    rotationIK += MathUtil::atan2(ty, tx) * MathUtil::Rad_Deg;
    if (bone._ascaleX < 0) rotationIK += 180;
    if (rotationIK > 180)
        rotationIK -= 360;
    else if (rotationIK < -180)
        rotationIK += 360;
    float sx = bone._ascaleX;
    float sy = bone._ascaleY;
    if (compress || stretch) {
        switch (bone._data.getTransformMode()) {
            case TransformMode_NoScale:
            case TransformMode_NoScaleOrReflection:
                tx = targetX - bone._worldX;
                ty = targetY - bone._worldY;
            default:;
        }
        float b = bone._data.getLength() * sx, dd = MathUtil::sqrt(tx * tx + ty * ty);
        if (((compress && dd < b) || (stretch && dd > b)) && (b > 0.0001f)) {
            float s = (dd / b - 1) * alpha + 1;
            sx *= s;
            if (uniform) sy *= s;
        }
    }
    bone.updateWorldTransform(bone._ax, bone._ay, bone._arotation + rotationIK * alpha, sx, sy, bone._ashearX, bone._ashearY);
}

void IkConstraint::apply(Bone &parent, Bone &child, float targetX, float targetY, int bendDir, bool stretch, float softness, float alpha) {
    float a, b, c, d;
    float px, py, psx, sx, psy;
    float cx, cy, csx, cwx, cwy;
    int o1, o2, s2, u;
    Bone *pp = parent.getParent();
    float tx, ty, dx, dy, dd, l1, l2, a1, a2, r, td, sd, p;
    float id, x, y;
    if (alpha == 0) {
        child.updateWorldTransform();
        return;
    }
    if (!parent._appliedValid) parent.updateAppliedTransform();
    if (!child._appliedValid) child.updateAppliedTransform();
    px = parent._ax;
    py = parent._ay;
    psx = parent._ascaleX;
    sx = psx;
    psy = parent._ascaleY;
    csx = child._ascaleX;
    if (psx < 0) {
        psx = -psx;
        o1 = 180;
        s2 = -1;
    } else {
        o1 = 0;
        s2 = 1;
    }
    if (psy < 0) {
        psy = -psy;
        s2 = -s2;
    }
    if (csx < 0) {
        csx = -csx;
        o2 = 180;
    } else
        o2 = 0;
    r = psx - psy;
    cx = child._ax;
    u = (r < 0 ? -r : r) <= 0.0001f;
    if (!u) {
        cy = 0;
        cwx = parent._a * cx + parent._worldX;
        cwy = parent._c * cx + parent._worldY;
    } else {
        cy = child._ay;
        cwx = parent._a * cx + parent._b * cy + parent._worldX;
        cwy = parent._c * cx + parent._d * cy + parent._worldY;
    }
    a = pp->_a;
    b = pp->_b;
    c = pp->_c;
    d = pp->_d;
    id = 1 / (a * d - b * c);
    x = cwx - pp->_worldX;
    y = cwy - pp->_worldY;
    dx = (x * d - y * b) * id - px;
    dy = (y * a - x * c) * id - py;
    l1 = MathUtil::sqrt(dx * dx + dy * dy);
    l2 = child._data.getLength() * csx;
    if (l1 < 0.0001) {
        apply(parent, targetX, targetY, false, stretch, false, alpha);
        child.updateWorldTransform(cx, cy, 0, child._ascaleX, child._ascaleY, child._ashearX, child._ashearY);
        return;
    }
    x = targetX - pp->_worldX;
    y = targetY - pp->_worldY;
    tx = (x * d - y * b) * id - px, ty = (y * a - x * c) * id - py;
    dd = tx * tx + ty * ty;
    if (softness != 0) {
        softness *= psx * (csx + 1) / 2;
        td = MathUtil::sqrt(dd), sd = td - l1 - l2 * psx + softness;
        if (sd > 0) {
            p = MathUtil::min(1.0f, sd / (softness * 2)) - 1;
            p = (sd - softness * (1 - p * p)) / td;
            tx -= p * tx;
            ty -= p * ty;
            dd = tx * tx + ty * ty;
        }
    }
    if (u) {
        float cosine;
        l2 *= psx;
        cosine = (dd - l1 * l1 - l2 * l2) / (2 * l1 * l2);
        if (cosine < -1)
            cosine = -1;
        else if (cosine > 1) {
            cosine = 1;
            if (stretch) sx *= (MathUtil::sqrt(dd) / (l1 + l2) - 1) * alpha + 1;
        }
        a2 = MathUtil::acos(cosine) * bendDir;
        a = l1 + l2 * cosine;
        b = l2 * MathUtil::sin(a2);
        a1 = MathUtil::atan2(ty * a - tx * b, tx * a + ty * b);
    } else {
        a = psx * l2, b = psy * l2;
        float aa = a * a, bb = b * b, ll = l1 * l1, ta = MathUtil::atan2(ty, tx);
        float c0 = bb * ll + aa * dd - aa * bb, c1 = -2 * bb * l1, c2 = bb - aa;
        d = c1 * c1 - 4 * c2 * c0;
        if (d >= 0) {
            float q = MathUtil::sqrt(d), r0, r1;
            if (c1 < 0) q = -q;
            q = -(c1 + q) / 2;
            r0 = q / c2;
            r1 = c0 / q;
            r = MathUtil::abs(r0) < MathUtil::abs(r1) ? r0 : r1;
            if (r * r <= dd) {
                y = MathUtil::sqrt(dd - r * r) * bendDir;
                a1 = ta - MathUtil::atan2(y, r);
                a2 = MathUtil::atan2(y / psy, (r - l1) / psx);
                goto break_outer;
            }
        }
        {
            float minAngle = MathUtil::Pi, minX = l1 - a, minDist = minX * minX, minY = 0;
            float maxAngle = 0, maxX = l1 + a, maxDist = maxX * maxX, maxY = 0;
            c0 = -a * l1 / (aa - bb);
            if (c0 >= -1 && c0 <= 1) {
                c0 = MathUtil::acos(c0);
                x = a * MathUtil::cos(c0) + l1;
                y = b * MathUtil::sin(c0);
                d = x * x + y * y;
                if (d < minDist) {
                    minAngle = c0;
                    minDist = d;
                    minX = x;
                    minY = y;
                }
                if (d > maxDist) {
                    maxAngle = c0;
                    maxDist = d;
                    maxX = x;
                    maxY = y;
                }
            }
            if (dd <= (minDist + maxDist) / 2) {
                a1 = ta - MathUtil::atan2(minY * bendDir, minX);
                a2 = minAngle * bendDir;
            } else {
                a1 = ta - MathUtil::atan2(maxY * bendDir, maxX);
                a2 = maxAngle * bendDir;
            }
        }
    }
break_outer : {
    float os = MathUtil::atan2(cy, cx) * s2;
    a1 = (a1 - os) * MathUtil::Rad_Deg + o1 - parent._arotation;
    if (a1 > 180)
        a1 -= 360;
    else if (a1 < -180)
        a1 += 360;
    parent.updateWorldTransform(px, py, parent._rotation + a1 * alpha, sx, parent._ascaleY, 0, 0);
    a2 = ((a2 + os) * MathUtil::Rad_Deg - child._ashearX) * s2 + o2 - child._arotation;
    if (a2 > 180)
        a2 -= 360;
    else if (a2 < -180)
        a2 += 360;
    child.updateWorldTransform(cx, cy, child._arotation + a2 * alpha, child._ascaleX, child._ascaleY, child._ashearX, child._ashearY);
}
}

IkConstraint::IkConstraint(IkConstraintData &data, Skeleton &skeleton) : Updatable(),
                                                                         _data(data),
                                                                         _bendDirection(data.getBendDirection()),
                                                                         _compress(data.getCompress()),
                                                                         _stretch(data.getStretch()),
                                                                         _mix(data.getMix()),
                                                                         _softness(data.getSoftness()),
                                                                         _target(skeleton.findBone(
                                                                             data.getTarget()->getName())),
                                                                         _active(false) {
    _bones.ensureCapacity(_data.getBones().size());
    for (size_t i = 0; i < _data.getBones().size(); i++) {
        BoneData *boneData = _data.getBones()[i];
        _bones.add(skeleton.findBone(boneData->getName()));
    }
}

/// Applies the constraint to the constrained bones.
void IkConstraint::apply() {
    update();
}

void IkConstraint::update() {
    switch (_bones.size()) {
        case 1: {
            Bone *bone0 = _bones[0];
            apply(*bone0, _target->getWorldX(), _target->getWorldY(), _compress, _stretch, _data._uniform, _mix);
        } break;
        case 2: {
            Bone *bone0 = _bones[0];
            Bone *bone1 = _bones[1];
            apply(*bone0, *bone1, _target->getWorldX(), _target->getWorldY(), _bendDirection, _stretch, _softness, _mix);
        } break;
    }
}

int IkConstraint::getOrder() {
    return _data.getOrder();
}

IkConstraintData &IkConstraint::getData() {
    return _data;
}

Vector<Bone *> &IkConstraint::getBones() {
    return _bones;
}

Bone *IkConstraint::getTarget() {
    return _target;
}

void IkConstraint::setTarget(Bone *inValue) {
    _target = inValue;
}

int IkConstraint::getBendDirection() {
    return _bendDirection;
}

void IkConstraint::setBendDirection(int inValue) {
    _bendDirection = inValue;
}

float IkConstraint::getMix() {
    return _mix;
}

void IkConstraint::setMix(float inValue) {
    _mix = inValue;
}

bool IkConstraint::getStretch() {
    return _stretch;
}

void IkConstraint::setStretch(bool inValue) {
    _stretch = inValue;
}

bool IkConstraint::getCompress() {
    return _compress;
}

void IkConstraint::setCompress(bool inValue) {
    _compress = inValue;
}

bool IkConstraint::isActive() {
    return _active;
}

void IkConstraint::setActive(bool inValue) {
    _active = inValue;
}

float IkConstraint::getSoftness() {
    return _softness;
}

void IkConstraint::setSoftness(float inValue) {
    _softness = inValue;
}
